The `maybe` in the article allows for this ambiguous situation:

    var fn = function (a, b) { ... };
    var maybe_fn = maybe(fn);
    var obj = {};
    maybe_fn(1);  // calls fn
    maybe_fn(1, null);  // doesn't call fn
    maybe_fn(1, obj.nonexistent_prop);  // also doesn't call fn

In my mind, all of these calls to `maybe_fn` should do the same thing. Maybe not, though?